Congruence

class Congruence : public libsemigroups::CongruenceInterface

Defined in cong.hpp.

On this page we describe the functionality relating to the Congruence class. This class can be used for computing a congruence over a semigroup by running every applicable algorithm from libsemigroups (and some variants of the same algorithm) in parallel. This class is provided for convenience, at present it is not very customisable, and lacks some of the fine grained control offered by the classes implementing individual algorithms, such as congruence::ToddCoxeter and congruence::KnuthBendix.

See also

congruence_kind and tril.

Example

FpSemigroup S;
S.set_alphabet(3);
S.set_identity(0);
S.add_rule({1, 2}, {0});
S.is_obviously_infinite();  // false

Congruence cong(twosided, S);
cong.add_pair({1, 1, 1}, {0});
cong.number_of_classes(); // 3

Member types

class_index_type	Type for indices of congruence class indices.
const_iterator
non_trivial_class_iterator
non_trivial_classes_type
options
options::runners

Constructors

Congruence(congruence_kind, FpSemigroup&)
Congruence(congruence_kind, T const&)
Congruence(congruence_kind, options::runners)
Congruence(congruence_kind, std::shared_ptr<FroidurePinBase>)

Deleted constructors

Congruence() = delete	Deleted.
Congruence(Congruence const&) = delete	Deleted.
Congruence(Congruence&&) = delete	Deleted.
operator=(Congruence const&) = delete	Deleted.
operator=(Congruence&&) = delete	Deleted.

Member functions

add_runner(T const&)
has_kambites() const
has_knuth_bendix() const
has_todd_coxeter() const
kambites() const
knuth_bendix() const
max_threads() const noexcept
max_threads(size_t) noexcept
todd_coxeter() const

Member functions inherited from CongruenceInterface

add_pair(std::initializer_list<size_t>, std::initializer_list<size_t>)
add_pair(word_type const&, word_type const&)
cbegin_generating_pairs() const noexcept
cbegin_ntc()
cend_generating_pairs() const noexcept
cend_ntc()
class_index_to_word(class_index_type)
const_contains(word_type const&, word_type const&) const override
contains(word_type const&, word_type const&) override
has_parent_fpsemigroup() const noexcept
has_parent_froidure_pin() const noexcept
has_quotient_froidure_pin() const noexcept
is_quotient_obviously_finite()
is_quotient_obviously_infinite()
kind() const noexcept
less(word_type const&, word_type const&)
non_trivial_classes()
number_of_classes()
number_of_generating_pairs() const noexcept
number_of_generators() const noexcept
number_of_non_trivial_classes()
parent_fpsemigroup() const
parent_froidure_pin() const
quotient_froidure_pin()
set_number_of_generators(size_t)
word_to_class_index(word_type const&)

Member functions inherited from Runner

dead() const noexcept
finished() const
kill() noexcept
report() const
report_every() const noexcept
report_every(TIntType)
report_every(std::chrono::nanoseconds)
report_why_we_stopped() const
run()
run_for(TIntType)
run_for(std::chrono::nanoseconds)
run_until(T&&)
run_until(bool(*)())
running() const noexcept
running_for() const noexcept
running_until() const noexcept
started() const
stopped() const
stopped_by_predicate() const
timed_out() const